It ringed a distant bell related to one of the OAuth grant types — the client credentials. To quote the specs:

Client credentials are used as an authorization granttypically when the client is acting on its own behalf (the client isalso the resource owner) or is requesting access to protectedresources based on an authorization previously arranged with theauthorization server.

From other recon results I knew that this company is built on top of Microsoft Azure therefore I searched for OAuth integration documentation. Now I just wanted to check if prodClientId and prodClientSecret are still valid: